黔西高原MIS3-MIS2期炭屑记录与火灾模式研究

火灾与气候、植被存在复杂的关系,搞清东亚季风区的火灾模式及其发生机制,对预测未来气候变化及火灾防治具有重要意义。通过对黔西高原MIS3—MIS2期间的古湖相沉积物进行炭屑分析并结合AMS~(14)C测年数据研究发现:MIS3晚期以来研究区的火灾主要发生于36.3—35 cal ka BP、26.2—17.6 cal ka BP期间,中粒炭屑和大炭屑分别在35、26.2、23.6 cal ka BP记录到3次地方火。研究区炭屑记录对冷干事件响应敏感,炭屑峰值区对应Heinrich事件(H事件)、末次冰盛期(LGM)等干旱事件,低值区对应DO事件,呈现千年旋回的特征。比对东亚地区的炭屑记录发现,在大范围的东亚季风区MIS2期比MIS3末期在火的强度和频率上都要高,与欧洲模式显著不同。火的发生机制可能受气候因素的控制,同时受植被类型的影响。

Fire history can be obtained from the charcoal record on the southwest plateau of Guizhou

Fire has a nonlinear relationship with climate and vegetation. Therefore, identifying the mode and mechanisms of fire in the East Asian monsoon area is very important when attempting to predict future climate change and improve fire management. A 110 cm continuous core from the southwest plateau of Guizhou was sampled at 1 cm intervals for charcoal analysis. The chronology of the core extended from MIS3 to MIS2. The results show that since the late MIS3, fire mainly happened in the 36.3-35 cal ka BP and 26.2-17.6 cal ka BP periods. Three local fires happened in the 35 cal ka BP, 26.2 cal ka BP, and 23.6 cal ka BP periods, and these were identified from the large and medium size charcoal particles. Comparison of the charcoal record with stalagmite and ice core records indicated that the peak in the charcoal record corresponds to cold-dry events, such as Heinrich and Last Glacial Maximun (LGM), and the low value area corresponds to DO events. These results have Millennium oscillation characteristics. A comparison with other charcoal records for the East Asian monsoon area showed that the intensity and frequency of fire in MIS2 was much stronger than in the late MIS3, which differs from the European pattern. The fire mechanism may be controlled by climatic factors and could be influenced by vegetation type.